Safety device



June 13, 193. N. c. COOPER 9 9 SAFETY DEVICE Filed Sept. 17, 1956 NELSON C. mmPER AT ORE Patented June 13, 1933 umrao STATES 2.10am v ears-n nsvrca Nelson 0. cooper, Marshallton, DeL, aaaignor-to E. I. du Pont de Nemours a Company, Wilmington, Del, a corporation of Delaware Application September 17, 1938, Serial No. 101,292 4 Claims. (L 68-209) This invention relates to a safety device for apparatus involving the use of liquid solvents, and is particularly directed to the elimination of fire hazards in the operation of dry-cleaning 5 machines and related types or equipment.

i In the dry cleaning of garments and other textile materials, as practiced in the early days of the art, practically the only solvents employed were various natural hydrocarbon distillates such asgasoline, naphtha, benzol and the like. These solvents are inexpensive; they possess adequate solvent power for grease and are generally satisfactory for dry-cleaning purposes except for one outstanding disadvantage. This isthe fact that they are highly inflammable and their vapors form explosive mixtures with air. Inasmuch as the usual dry-cleaning processes involve the operations of heating and distilling the solvent, a dry-cleaning establishment utilizing highly inflammable solvents constitutes a very serious flre risk.

As a result of the increased recognition of the hazards attending the use of inflammable drycleaning solvents, there has been a marked trend in recent years toward the replacement of the natural hydrocarbon distillates by synthetic, non-flammable solvents. The non-flammable solvents which have thus far come into practical use are the various chlorinated hydrocarbons, of which the outstanding examples are carbon tetrachloride, trichlorethylene, and perchlorethylene, These solvents are non-flammable and incapable of forming explosive mixtures under the conditions of dry-cleaning operation; hence their use effectively eliminates all fire and explosion hazards in dry-cleaning establishments insofar as the solvent is concerned.

Nevertheless, fire underwriters and rating bureaus of flre insurance companies have hesitated to extend to dry-cleaning equipment designed for use with non-flammable solvents the favorable lire-risk rating to which it would normally be entitled as a result of, the non-flammable character of the solvent employed. The reason for this is simply the fact that, although a particular cleaning apparatus may be intended for use with non-flammable solvents, there is nothing inherent in its construction which would 50 prevent its operation with inflammable solvents. Thus the operator of an approved machine, through ignorance, inadvertence or a desire to economize on solvent costs, might operate the machine with an inflammable solvent with the .55 probability that the fire risk would be even greater than if the machine had been designed for use with inflammable solvents.

It is, therefore, theprincipal object of the present invention to provide a device suitable for\ installation on dry-cleaning machines and apl5 paratus of related character, which will permit the normal functioning of the machine when sup- 1 plied with a. non-flammable solvent but which will prevent operation of the machine with inflammable solvents. Other objects and advanl0 tages of the invention will be apparent from the ensuing description thereof.

The invention is fundamentally based upon the fact that the inflammable solvents, as a class, are characterized by having an appreciably lower 15 specific gravity than the non-flammable solvents which are available for dry-cleaning purposes. Thus, petroleum and coal tar distillates, such as the various naphtha, gasoline and benzol fractions, are all lighter than water and, in general, 20 have specific gravities ranging from about 0.8 to about 0.9. On the other hand, the non-flammable chlorinated hydrocarbon solvents which are available for dry-cleaning purposes are all heavier than water. Thus, carbon tetrachloride has a speciflc gravity of about 1.58; trichloretlsilylene about 1.46; and percblorethylene about 1.

Accordingly, the present invention contemplates broadly the provision on dry-cleaning ma- 30 chines and apparatus of related character of means responsive to the density of the solvent employed whereby the machine may be rendered inoperative when the density of the solvent falls below a predetermined minimum value.

The appended drawing depicts a diagrammatic cross-sectional representation of a device embodying the invention, comprising an automatic float valve mechanism adapted to be installed in a line supplying solvent to a dry-cleaning appa- 40 ratus or in any solvent circuit in the apparatus where a cessation of the flow of solvent would prevent the functioning of the apparatus.

Referring to the drawing, the reference character l designates a float chamber provided with a solvent inlet connection 2 and a solvent outlet connection 3. Within the float chamber is a float member 4 which may be in the form of a hollow metal sphere of a density such that it will float in chlorinated hydrocarbon solvents but will sink in natural hydrocarbon distillates. In the lower portion of the float chamber is positioned an annular seat 5 adapted to receive the float member 4 and thereby stop the flow of solvent through the float chambera In the normal operation of the device, a chlorinated hydrocarbon solvent enters the float chamber I through the inlet connection 2, thence passes downward through the central opening in the seat I and out through the exit connection 8. The float member 4, being lighter than the solvent, assumes a position in the extreme upper part oi the float chamber as indicated by the full lines in the drawing. Ii, however, an inflammable solvent of low density is admitted to the float chamber, the float member 4 will sink in the surrounding medium and descend to engage the seat I, as shown by the dotted lines in the drawing, and thus stop the flow of solvent through the central opening in the seat I. The apparatus is thus rendered inoperative as soon as a light inflammable solvent is admitted to the float chamber.

The float member 4 may be constructed so as to have a speciflc gravity anywhere within the range between that of the non-flammable solvent which is designed to be used in the particular apparatus concerned, and the maximum speciflc gravity oi the usual inflammable solvents. Thus, a float for a perchlorethylene machine should have a speciflc gravity between 0.9 and 1.6. For maximum safety, however, it is desirable that the speciflc gravity of the float be somewhat near the upper limit of the permissible speciflc gravity range, e. g., the float for a perchlorethvlene machine may suitably have a speciflc gravity of about 1.45, while in a trichlorethylene machine a speciflc gravity oi 1.35 for the float would be suitable. For machines designed for use with all types oi chlorinated hydrocarbon solvents it may be desirable further to reduce the speciflc gravity of the float to about 1.2 or less.

Obviously, a number of equivalents of the fore-- going specific embodiment oi the invention will be immediately apparent to those skilled in the art. For example, the particular form of the invention that has just been described employs a single element which acts both as a float responsive to variations in the density of the solvent and also as a shut-oil valve in a solvent supply or circulation line: however, a float may be used which is operatively connected to an entirely separate shut-oil. valve, or to electrical switches which stop the supply of power to solvent pumps or other parts of the equipment, or to other mechanism adapted to stop the operation of the apparatus concerned. Furthermore, although the device of the invention has been described with particular reference to its utilization in drycleaning equipment, it will be obvious that it can solvent for stopping also be used to advantage in a variety of other types 01 equipment designed to employ non-flammable solvents, as for example in the fleld of metal decreasing and in solvent extraction processes in general.

Accordingly, it is to be understood that the invention is not restricted to the speciflc embodiments and flelda or application thereof described heroinabove, but includes all such variations, modifications and equivalents as fall within the scope oi the appended claims.

' I claim:

1. In a dry-cleaning machine, means for supplying liquid solvent thereto, and means responsive to variations in the densiy 01' said liquid the flow thereof to said machine when the density oi. said solvent falls below a predetermined value.

2. In combination with a dry-cleaning machine having a conduit for supplying liquid solvent thereto, a device operatively associated with said conduit comprising a member responsive to variationg in the density oi said liquid solvent, and means cooperating with said member to prevent flow oi solvent through said conduit when the density of said solvent falls below a predetermined value.

3, In combination with a dry-cleaning machine having a conduit for supplying liquid solvent thereto, a float chamber interposed in and forming a part of said conduit, a float movable within float-chamber to assume a floating position in the presence 01' a relatively heavy liquid and to assume a non-floating position in the presence oi a lighter liquid, and a seat to receive said float and thereby to prevent flow of liquid through said float-chamber when said float is in nonfloating position.

4. In combination with a dry-cleaning machine having a conduit for supplying liquid solvent thereto, a float-chamber interposed in and forming a part of said conduit, 9. float having a predetermined speciflc gravity within the range of 0.9 to 1.6, said float being movable within said float-chamber the presence of a liquid having a specific gravity exceeding said predetermined value and to assume a non-floating position in the presence of a liquid of specific gravity less than said predetermined value, and a seat to receive said float and thereby to prevent flow of liquid through said float-chamber when said float is in non-fioating position.

NELSON C. COOPER.

to assume a floating position in. 

